import numpy as  np

arr2d = np.array([[1,6,11,21],[1,5,65,55],[5,85,52,5],[5,8,8,8]])

print(arr2d)
print(arr2d[1,2])
print(arr2d[:2])
print(arr2d[:,2])
print(arr2d[1,1])
print(arr2d[2])
print(arr2d[:2,:2])